The maneuvering ability of articulated vehicles such as tractor-trailer combinations is often hampered by the difficulty in quickly and conveniently determining the location of the rear end of the trailer and in viewing the area behind the rear end of the trailer This is particularly so when the trailer is long and the tractor is turning toward the right. Typically, externally mounted side mirrors are placed on both sides of the tractor. These mirrors are rigidly positioned for straight ahead driving. Therefore, during turns, one mirror provides a view of the side of the trailer while the other mirror provides a view of the area to the side of the trailer. Neither of these views are useful. The much needed view of the rear of the trailer is not provided.
Although the driver can view the left rear end of the trailer and behind it by looking out the left window when the trailer is turning toward the left, the driver must turn his head and divert his attention away from the front of the vehicle. The driver's peripheral vision may not provide immediate perception of events occurring at the front of the vehicle. Moreover, the driver is unable to peer out the right window and view the right rear end of the trailer during a right turn. Stationary mirrors are also deficient when a tractor-trailer is backing into a loading or unloading area such as a dock during an attempt to park. In these situations, the tractor is almost always at an acute angle relative to the trailer to facilitate the docking maneuver. Stationary mirrors do not permit the rear of the trailer to be viewed during parking as the angle between the tractor and the trailer do not provide such a view. It is often necessary for the driver to leave the vehicle or to obtain the assistance of an additional person to perform the backing and parking maneuvers.
In view of these problems, numerous attempts have been made to provide a mirror which pivots or rotates to provide a view of the rear of a trailer during turns. Some of these prior art systems are disclosed in U.S. Pat. Nos. 2,988,957; 3,469,901; 3,527,528; 3,536,382; 3,749,480; 4,609,265; 4,632,525. Many of these devices require complex mechanical devices with or without complicated electric circuits to rotate the side mirrors. Many devices are operated based on the angle between the tractor and the trailer as measured at the fifth wheel of the tractor. Some devices are activated by the turn signal of the vehicle. Further, many of these systems include components which are mounted on both the tractor and the trailer. This requires that system components be removed and remounted each time a tractor is coupled to a different trailer. Finally, the known devices are generally very complicated.